Containers having steel ends are used for foods such as instant coffee, baby formulas and soup mixes. The containers may have tin-plated steel bodies or composite, spiral wound bodies with a steel ring around an open end portion of the container.
Peelable and heat sealable lids for steel end containers are known in the prior art. However, there is still a need to provide such containers with lids having the following combination of properties: (a) approximately constant peel strength over a wide range of heat seal temperatures; (b) cohesive failure in the heat seal layer upon peeling; and (c) high burst strength in the sealed lid.
A principal objective of the present invention is to provide a film suitable for making steel end container lids having a combination of constant peel strength, cohesive failure in the seal layer and high burst strength.
A relative objective of the invention is to provide lidstock material comprising a substrate laminated with a film containing a mixture of an ethylene-carboxylic acid copolymer, polybutylene, and a particulate inorganic filler.
Additional objectives and advantages of my invention will become apparent to persons skilled in the art from the following detailed description.